Sterilization is a term referring to any process that eliminates (removes) or kills microbial life, including transmissible agents (such as fungi, bacteria, viruses, or spore forms) present on a surface, or contained in a fluid, or in medication, or in a compound such as biological culture media. Sterilization can be achieved by applying heat, chemicals, irradiation, high pressure, and filtration or combinations thereof.
In general, surgical instruments and medications that enter an already aseptic part of the body (such as the bloodstream, or penetrating the skin) must be sterilized to a high sterility assurance level. Examples of such instruments include scalpels, hypodermic needles and implantable medical devices (IMD), such as artificial pacemakers.
A widely used method for heat sterilization is the autoclave, sometimes referred to as a converter. Autoclaves commonly use steam heated to 121-134° C. To achieve a degree of sterility, a holding time of at least 15 minutes at 121° C. at 100 kPA, or 3 minutes at 134° C. at 100 kPa is required. Additional sterilizing time is usually required for liquids and instruments packed in layers of cloth, as they may take longer to reach the required temperature.
One method of sterilization involves passing steam through a cabinet. For effective sterilization, steam needs to penetrate the cabinet load uniformly. Accordingly, the cabinet must not be overcrowded, and the lids of bottles and containers must be left ajar. During the initial heating of the chamber, residual air must be removed. Indicators should be placed in the most difficult places for the steam to reach to ensure that steam actually penetrates there.
A filter is typically placed over the vent to keep particles or extraneous materials from entering the cabinet before, during or after the sterilizing process. Once the sterilizing process is completed the filter needs to be removed and inspected by medical professionals to verify the integrity of the sterilizing process was maintained. If it is discovered during inspection that the filter did not remain intact, the sterilizing process has to be repeated with a new filter.